<!DOCTYPE html>
<html lang="zh">
<head>
    <meta charset="UTF-8">
    <title>02-before-after</title>
    <style>
        /*div::before {
            content: "666";
            color: blue;
        }

        div::after {
            content: "777";
            color: orange;
        }*/

        /*
        浮动、定位
        */

        div {
            color: red;
        }

        div::before {
            content: url("images/5.gif");
            width: 20px;
            height: 20px;
        }
    </style>
</head>
<body>

<div>我是div</div>

</body>
</html>